The present invention relates generally to leads for conducting electrical signals to and from the heart. More particularly, it pertains to a high impedance electrode assembly for delivering electrical charges to and from the heart.
Leads implanted in or about the heart have been used to reverse certain life threatening arrhythmias, or to stimulate contraction of the heart. Electrical energy is applied to the heart via the leads to return the heart to normal rhythm. Leads have also been used to sense in the atrium or ventricle of the heart and to deliver pacing pulses to the atrium or ventricle.
Cardiac pacing may be performed by the transvenous method or by leads implanted directly onto the epicardium. Permanent transvenous pacing is performed using a lead positioned within one or more chambers of the heart. A lead may be positioned in the ventricle or in the atrium through a subclavian vein, and the lead terminal pins are attached to a pacemaker which is implanted subcutaneously. The lead provides the electrical connection between the pulse generator and the heart tissue which is to be excited.
The pacemaker includes a power source for the electrical energy which is applied to the heart from the pacemaker. Since pulse generators are implanted subcutaneously within the patient, it is undesirable when excessive current drain is placed on the power source for the pacemaker. High stimulation thresholds can in result in excessive current drain from the power source. In addition, larger surface areas of electrodes require larger amounts of energy to deliver pacing pulses. A shorter battery life for a pacemaker also results increased number of medical procedures for the patient. The increased number of medical procedures result in increased risk and cost to the patient.
Accordingly, there is a need for a high impedance electrode for pacing and/or sensing the atrium and/or the ventricle. In addition, there is a need for an electrode which does not excessively drain the power source of a pacemaker.
A lead assembly includes a lead body which extends from a proximal end to a distal end. The lead body has at least one conductor and the body is defined in part by a circumference. At least one electrode is electrically coupled with the conductor, where the electrode comprises a wire filament disposed about the circumference of the lead body. The wire filament is bonded with the lead body. In one embodiment, a conductor coil is disposed within the lead body, where a portion of the conductor coil extends through the lead body and around the circumference of the lead body to form the wire filament disposed about the lead body.
In another embodiment, a lead assembly has a lead body which extends from a proximal end to a distal end and defined in part by a circumference. The lead body has a conductor coil, and an electrode assembly including at least one electrode electrically coupled with the conductor coil. The electrode comprises a conductive sleeve which is partially masked by the lead body.
The lead assembly further includes, in another embodiment, at least one drug elution collar adjacent to the electrode. In yet another embodiment, the lead assembly further includes a first drug elution collar and a second drug elution collar. The first drug elution collar and the second drug elution collar straddle the exposed electrode surface. In one embodiment, the first drug elution collar has a first drug therein, the second drug elution collar has a second drug therein, and the first drug is different than the second drug. The lead further comprises a porous member disposed on the lead body proximate to the electrode.
In yet another embodiment, the lead assembly includes an electrode having an exposed electrode surface, where the exposed electrode surface is offset from a surface of the lead body. Alternatively, the exposed electrode surface is flush with a surface of the lead body. The exposed electrode surface, in another embodiment, extends about the circumference of the lead body.
In another embodiment, a lead assembly includes a lead body which extends from a proximal end to a distal end. The lead body has a conductor coil and an electrode is electrically coupled with the conductor. The electrode has a high pacing impedance, where the electrode has a surface area less than about 1.2 mm2. In one embodiment, the electrode comprises a conductive sleeve partially masked by the lead body. Optionally, at least one drug elution collar is disposed adjacent to the electrode. The drug elution collar includes a first drug elution collar and a second drug elution collar, where each collar is disposed on opposite sides of the sleeve. In one embodiment, the first drug elution collar has a first drug which is different than a second drug of the second drug elution collar. The lead assembly, in another embodiment, further includes a porous member on the lead body proximate to the electrode.
In yet another embodiment, the lead assembly includes an electrode having an exposed electrode surface, where the exposed electrode surface is offset from a surface of the lead body. Alternatively, the exposed electrode surface is flush with a surface of the lead body. The exposed electrode surface, in another embodiment, extends about the circumference of the lead body. In another embodiment, a conductor coil is disposed within the lead body, where a portion of the conductor coil extends through the lead body and around the circumference of the lead body to form the wire filament disposed about the lead body. Optionally, the wire filament is bonded with the lead body.
These and other embodiments, aspects, advantages, and features of the present invention will be set forth in part in the description which follows, and in part will become apparent to those skilled in the art by reference to the following description of the invention and referenced drawings or by practice of the invention. The aspects, advantages, and features of the invention are realized and attained by means of the instrumentalities, procedures, and combinations particularly pointed out in the appended claims and their equivalents.